Key switch device for electronic musical instruments

ABSTRACT

A key switch device for an electronic musical instrument having a frame body made, for example, of plastics material having at least one longitudinal member and a pair of spaced lateral members extending at right angles to the longitudinal member. A plurality of movable contact members fixed to the longitudinal member and arranged in a juxtaposed relationship. At least one elongated fixed contact member fitted at both ends thereof to the lateral members, and extending transversely of the movable contact members. Actuators provided for the respective movable contact members, whereby the relative position of the movable and fixed contact members can be easily secured. By superposing a plurality of key switch devices of the same construction, a multiple contact key switch may be readily obtained.

United States Patent July 25, 1969, Japan, No. 44/70475; July 25, 1969, Japan, No. 44/70476; July 25, 1969, Japan, No. 44/70477; Aug. 19, 1969, Japan, No. 44/78200; Aug. 19, 1969, Japan, No. 44/78201 KEY SWITCH DEVICE FOR ELECTRONIC MUSICAL INSTRUMENTS 12 Claims, 14 Drawing Figs.

US. Cl 200/166 J, 335/135, 200/166 PC Int. Cl I-I0lh 9/00 Field of Search 200/ l 66 J,

Primary Examiner-H. 0. Jones A!torney-Kemon, Palmer & Estabrook ABSTRACT: A key switch device for an electronic musical instrument having a frame body made, for example, of plastics material having at least one longitudinal member and a pair of spaced lateral members extending at right angles to the iongitudinal member. A plurality of movable contact members fixed to the longitudinal member and arranged in ajuxtaposed relationship. At least one elongated fixed contact member fitted at both ends thereof to the lateral members, and extendingtransversely of the movable contact members. Actuators provided for the respective movable contact members, whereby the relative position of the movable and fixed contact members can be easily secured. By superposing a plurality of key switch devices of the same construction, a multiple contact key switch may be readily obtained.

PATENTEDNU 2 3. 622.729

' sum 1 OF 3 INVENTOR.

PATENTEDNUV 23 [SH SHEET 2 BF 3 FIG. 6

FIG. 7

SUMMARY OF THE INVENTION The present invention relates to improvements in an electronic musical instrument, and particularly to its key switch device.

A key switch device of such kind involves a large number of contact units associated with the keys of the musical instrument. Particularly a high grade musical instrument involves a series of interlocking multicircuit multicontact key switches resulting in a complicated assembly and construction. Accordingly, there has been demanded some means for eliminating such difficulties from the standpoint of quantity productron.

. The present invention has been accomplished in view of the aforementioned situation and is primarily intended to provide a key switch device for electronic musical instruments wherein the construction thereof is so improved as to easily set the relative position of movable and fixed contact members involved, consequently realize their quantity production and prominently facilitate their assembly. It is further intended to provide a key switch device so designed as to ease the superposition of the key switch device on another key switch device of the same construction whereby a multiple contact key switch can be readily constructed.

In an aspect of the present invention, there is provided a key switch device for an electronic musical instrument comprising a frame body of electrically insulating material having at least one longitudinal member and a pair of spaced lateral members disposed substantially at right angles to said longitudinal member; a plurality of movable contact members of elastic conductive material mutually spaced at a prescribed interval and extending from the longitudinal member substantially at right angles thereto with base ends thereof being fixed to the longitudinal member; at least one longitudinally elongated fixed contact member of electrically conductive material disposed substantially parallel with the longitudinal member so as to face the movable contact members, both ends of said fixed contact member being fitted to the lateral members; and actuators provided for the movable contact members so as to urge them to the longitudinally elongated fixed contact member.

BRIEF EXPLANATION OF THE DRAWINGS FIGS. 1A and 1B respectively are a plan view of a key switch device according to an embodiment of the present invention and a sectional view thereof on line lB-IB;

FIG. 2 is a fragmental perspective view, in an enlarged scale, of the key switch device shown in FIG. 1;

FIG. 3 is a cross-sectional view of a plurality of said key switch devices assembled into an interlocking multicircuit multicontact key switch when fitted to the keyboard on an electronic musical instrument;

FIG. 4 is a fragmental perspective view of a movable contact member fitted to the frame body of a key switch device according to another embodiment of the invention;

FIGS. 5A and 58 respectively are an exploded perspective view and a cross-sectional view of a movable contact member to be fitted to the frame of a key switch device according to still another embodiment of the invention;

FIG. 6 is a cross-sectional view of a plurality of key switch devices assembled into an interlocking multicircuit multicontact key switch using actuators of different construction according o the present invention;

FIG. 7 is a partly exploded fragmental perspective view, in an enlarged scale, of the key switch device as shown in FIG. 6;

FIGS. 8A and 8B respectively are elevational and cross-sectional views of an actuator fitted in another form;

FIGS. 9A and 98 respectively are elevational and cross-sectional views on line 9B9B thereof of the actuator of FIG. 8 showing its modification; and

FIG. 10 is a fragmentary perspective view of the key switch devices assembled into an interlocking multicircuit multicontact key switch where there are incorporated printed circuit boards to connect the key switch devices.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 2, there is shown a key switch device of the invention in which a frame body 10 consists of a main longitudinal member 11, main lateral members 12 extending from both ends of the main longitudinal member 1 I at right angles thereto, a reinforcing longitudinal member 13 and reinforcing lateral members 14, all these members being integrally prepared from electrically insulating material such as plastics material. Numeral 15 represents movable contact members or strips of electrically conductive elastic material such as nickel silver spatially arranged in parallel at right angles to the main longitudinal member 11, the base end of each contact strip 15 being embedded in the main longitudinal member 11 by insert molding when the frame body 10 is fabricated. Further, there are disposed two longitudinally elongated fixed contact members 16 and 16 extending parallel to the main longitudinal member 11 with the free ends of the movable contact strips 15 interposed therebetween. Of course, only one fixed contact member may be disposed according to the necessity. Both ends of the fixed contact members 16 and 16' extend through an L-shaped groove 17 formed or bored on the ends of the lateral members 12 of the frame body 10. The L-shaped groove 17 consists of a groove 17a extending perpendicularly to the lengthwise direction of the lateral member 12 and groove 17b extending in the lengthwise direction of the lateral member 12, both grooves 17a and 17b being connected together to form a substantial L-shape. At the intermediate point of the movable contact strip 15 is positioned an actuator element I8 of an electrically insulating material such as plastics or rubber having the same height as that of the frame body 10 in a manner tightly to surround the movable contact strip 15. At suitable points on one side surface of the frame body 10 are formed locating projections 19 and on the opposite side surface thereof locating depressions 20, both the projections and the depressions being located at the corresponding parts of the frame body 10.

The key switch devices thus constructed may be superposed in a required number as shown in FIG. 3. In this case, the projection 19 of a given key switch device fits into the depression 20 of the adjacent device so as properly to set them in position, the entire assembly of the key switch devices being placed below keys 22 of an electronic musical instrument arranged in a row. With an interlocking multicircuit multicontact key switch 23 thus assembled, the actuators 18 of the superposed key switch devices contact each other to assume an interlocking relationship, so that when one of the keys 22 is depressed against the elastic force of a key spring 24, the corresponding actuators 18 grouped in a vertical line are urged downward by means of a projection 25 provided on the underside of the key 22 with the resultant interlocking operation of the corresponding movable contact strips 15.

The fixation of the movable contact strips 15 on the main longitudinal member 11 of the frame body 10 may be effected not only by the aforesaid insert molding but also any other means. FIGS. 4 and 5 illustrated such other means. In FIG. 4, a main longitudinal member 30 consisting of thermoplastic resin such as ABS (acrylonitrile-butadiene-styrene) resin is bored with a groove 32, which has a projection 31 integrally formed at the bottom thereof. A movable contact strip 33 is fitted into the groove 32 with the projection 31 inserted through a hole 34 perforated at the base end of the movable contact strip 33. The head of the projection 31 is pressed or deformed fiat under heat, thereby to fix the movable contact strip 33 to the main longitudinal member 30.

In FIG. 5, there is fonned in advance a groove 41 in a main longitudinal member 40 made of plastics material, the groove 41 extending transversely of the member 40. On both sides of the base end of a movable contact strip 42 are formed out and setup portions 43 in symmetrical relationship in a length substantially equal to, that is, not shorter than, the length of the groove 41 or the width of the main longitudinal member 40, said cut portions 43 being preferably provided with a toothed edge 44 (FIG. 5A). The movable contact strip 42 is forcefully pushed into the groove 41. Then the toothed edge 44 of the portion 43 bites into the opposite wall surfaces of the groove 41 (FIG. B), whereby attaining the fixation of the movable contact strip 42 to the main longitudinal member 40.

FIG. 6 represents an interlocking multicircuit multicontact key switch 51 using a plurality of key switch devices of another embodiment, which is placed below keys of an electronic musical instrument arranged in a row, where there are actuated a plurality of corresponding movable contact strips 52 by an actuator 53. With the key switch device of FIG. 6, a frame body 54 lacks, as shown in FIG. 7, the reinforcing longitudinal member used in the preceding embodiment. The movable contact strip 52 consisting of an elongated plate member whose base end is fixed to the frame body 54 is provided at the opposite or free end with notches 55 in symmetrical relationship on both sides of said end and a longitudinal slot 56 extending between the notches 55 and bifurcating the free end. The actuator 53 consists of an elongated plate member made of, for example, plastics material and is perforated with, for example, a plurality of rhombic holes 57 for permitting the free end of the movable contact strip 52 to be pushed therethrough with a prescribed force. In this case, the width of the movable contact strip 52 is made slightly larger than that of the rhombic hole 57. When, the end of the movable contact strip 52 is inserted through said rhombic hole 57 against the intrinsic elastic force of the strip 52 by reducing the width of the free end of the movable contact strip 52 which is bifurcated through the longitudinal slot 56, then the rhombic hole 57 fits into the notches 55 of the movable contact strip 52 to cause both members 52 and 53 to be easily joined with the least possibility of either of them falling off from each other.

FIGS. 8A and 8B show another method of coupling a movable contact strip 60 and an actuator 61 used in an interlocking multicircuit multicontact key switch employing the key switch devices of the invention. According to this embodiment, the actuator 61 consists of an elongated plate member made of electrically insulating material such as plastics, and is provided on its opposite sides with projected portions 62 and recessed portions 63 alternately arranged at a prescribed space. On the other hand, the movable contact strip 60 formed into an elongated plate member is perforated with a through hole 66 consisting of a longitudinal slot 64 extending lengthwise of the strip 60 and permitting the entire width, namely, the opposite projected portions 62, of the actuator 61 easily to pass therethrough and a round bore 65 communicating with the central part of the slot 64 and formed large enough to allow the recessed portions 63 to rotate therein but not to allow the projected portions 62 to pass therethrough. Therefore, the joining of the actuator 61 with the movable contact strip 60 may be efi'ected by inserting the actuator 61 through the slots 64 of the movable contact strips 60 arranged in a vertical line in the assembled multicontact device until the recessed portion 63 is set in the round hole 65, followed by 90 rotation of the actuator 61, Then as illustrated in FIG. 8B, the underside of the projected portion 62 of the actuator 61 contacts the upper surface of the movable contact strip 60, thereby attaining the tight coupling of both members 60 and 61.

The arrangement jointly shown by FIGS. 9A and 9B is not essentially different from that of FIG. 8. The point is, however, that the opposite recessed portions 73 of an actuator 71 assume a wedged form, thus offering convenience in properly locating a movable contact strip 70 when it is coupled with the actuator 71.

FIG. shows an interlocking multicircuit multicontact key switch employing a plurality of key switch devices described above in which there are incorporated well-known printed circuit boards. In this figure, the key switch devices are electrically connected to, and mechanically supported by, a printed circuit board 82 controlling wiring stretched across the movable contact strips 81 and another printed circuit board 84 controlling wiring stretched across the fixed contact strips 83. That is, the ends of the movable contact strips 81 and the fixed contact strips 83 are inserted in holes perforated in the printed circuit boards 82 and 84 respectively.

What is claimed is:

1. A key switch device for an electronic musical instrument comprising a frame body of electrically insulating material having at least one longitudinal member and a pair of spaced lateral members disposed substantially at right angles to said longitudinal member; a plurality of movable contact members of electrically conductive elastic material mutually spaced at a prescribed internal and extending from the longitudinal member substantially at right angles thereto with base ends thereof fixed to the longitudinal member; at least one longitudinally elongated fixed contact member of electrically conductive material disposed substantially parallel to the longitudinal member so as to face the movable contact members, both ends of said fixed contact member are fitted to the lateral members; and actuators provided for the movable contact members so as to urge them to the longitudinally elongated fixed contact member.

2. The key switch device according to claim 1 which further comprises projections formed on one side of said frame body and depressions formed on the opposite side thereof, both the projections and the depressions being located at the corresponding parts of the frame body.

3. The key switch device according to claim 2 wherein each of the actuators consists of a piece of electrically insulating material fixed to each movable contact member and having substantially the same height as that of the frame body.

4. The key switch device according to claim I wherein the members of the frame body are integrally prepared from plastics material.

5. The key switch device according to claim 4 wherein the base end of each movable contact member is embedded in the frame body by insert molding.

6. The key switch device according to claim 4 wherein the base end ofeach movable contact member is perforated with a hole, and there is integrally formed a projection on the longitudinal member corresponding to each movable contact member, said projection being inserted through the hole and deformed flat under heat so as to fix the movable contact member to the frame body.

7. The key switch device according to claim 4 wherein each of the movable contact members is provided on each side of its base end with a cut and setup portion of a length substantially equal to the width of the longitudinal member of the frame body, and the longitudinal member has a groove formed transversely thereof and corresponding to each movable contact member, said groove being defined by both vertical sidewalls, and said cut and setup portions being engaged with the sidewalls of the groove thereby to fix the movable contact member to the frame body.

8. The key switch device according to claim 1 wherein each of the movable contact members is provided on both sides of its free end with notches and a slot extending between said notches and bifurcating the free end and each of the actuators is perforated with a hole permitting the free end of the movable contact member to be pushed therethrough under a required force against the intrinsic elasticity of the movable contact member, thereby to fit the hole of the actuator into the notches so as to couple the actuator with the movable contact member with the least possibility of either of them falling from the other.

9. The key switch device according to claim 1 wherein both the movable contact members and the actuators consist of elongated plate members, there being formed projected and recessed portions on the opposite sides of the actuators, and each of the movable contact members being perforated with a I through hole consisting of a slot long enough to allow the passage of the entire width of each actuator and a round hole communicating with the central part of the slot and formed large enough to permit the recessed portions of the actuator to rotate therein but not to allow the passage of the projected portions thereof, whereby the actuator can be inserted in the movable contact member through the slot of the through hole until the recessed portion is set in the round hole, and is rotated within the round hole so as to allow the projected portion of the actuator to be in contact with the movable contact member, thereby to securely couple the actuator with the movable contact member.

10. The key switch device according to claim 9 wherein the recessed portions of the actuator assume a wedged form.

11. The key switch device according to claim 1 wherein the movable contact members are mechanically fixed to a printed circuit board and electrically connected thereto.

12. The key switch device according to claim 1 wherein the fixed contact member is mechanically fixed to a printed circuit board and electrically connected thereto. 

1. A key switch device for an electronic musical instrument comprising a frame body of electrically insulating material having at least one longitudinal member and a pair of spaced lateral members disposed substantially at right angles to said longitudinal member; a plurality of movable contact members of electrically conductive elastic material mutually spaced at a prescribed interval and extending from the longitudinal member substantially at right angles thereto with base ends thereof fixed to the longitudinal member; at least one longitudinally elongated fixed contact member of electrically conductive material disposed substantially parallel to the longitudinal member so as to face the movable contact members, both ends of said fixed contact member are fitted to the lateral members; and actuators provided for the movable contact members so as to urge them to the longitudinally elongated fixed contact member.
 2. The key switch device according to claim 1 which further comprises projections formed on one side of said frame body and depressions formed on the opposite side thereof, both the projections and the depressions being located at the corresponding parts of the frame body.
 3. The key switch device according to claim 2 wherein each of the actuators consists of a piece of electrically insulating material fixed to each movable contact member and having substantially the same height as that of the frame body.
 4. The key switch device according to claim 1 wherein the members of the frame body are integrally prepared from plastics material.
 5. The key switch device according to claim 4 wherein the base end of each movable contact member is embedded in the frame body by insert molding.
 6. The key switch device according to claim 4 wherein the base end of each movable contact member is perforated with a hole, and there is integrally formed a projection on the longitudinal member corresponding to each movable contact member, said projection being inserted through the hole and deformed flat under heat so as to fix the movable contact member to the frame body.
 7. The key switch device according to claim 4 wherein each of the movable contact members is provided on each side of its base end with a cut and setup portion of a length substantially equal to the width of the longitudinal member of the frame body, and the longitudinal member has a groove formed transversely thereof and corresponding to each movable contact member, said groove being defined by both vertical sidewalls, and said cut and setup portions being engaged with the sidewalls of the groove thereby to fix the movable contact member to the frame body.
 8. The key switch device according to claim 1 wherein each of the movable contact members is provided on both sides of its free end with notches and a slot extending between said notches and bifurcating the free end and each of the actuators is perforated with a hole permitting the free end of the movable contact member to be pushed therethrough under a required force against the intrinsic elasticity of the movable contact member, thereby to fit the hole of the actuator into the notches so as to couple the actuator with the movable contact member with the least possibility of either of them falling off from the other.
 9. The key switch device according to claim 1 wherein both the movable contact members and the actuators consist of elongated plate members, there being formed projected and recessed portions on the opposite sides of the actuators, and each of the movable contact members being perforated with a through hole consisting of a slot long enough to allow the passage of the entire width of each actuator and a round hole communicating with the central part of the slot and formed large enough to permit the recessed portions of the actuator to rotate therein but not to allow the passage of the projected portions thereof, whereby the actuator can be inserted in the movable contact member through the slot of the through hole until the recessed portion is set in the round hole, and is rotated within the round hole so as to allow the projected portion of the actuator to be in contact with the movable contact member, thereby to securely couple the actuator with the movable contact member.
 10. The key switch device according to claim 9 wherein the recessed portions of the actuator assume a wedged form.
 11. The key switch device according to claim 1 wherein the movable contact members are mechanically fixed to a printed circuit board and electrically connected thereto.
 12. The key switch device according to claim 1 wherein the fixed contact member is mechanically fixed to a printed circuit board and electrically connected thereto. 